Design Of Straight Down Type LED Backlight Optical System

The current display product category is very diverse,most of which use liquid crystal display.An important component of the optical system is the backlight optical system.LED has the characteristics of small size and compact structure.The LED backlight optical system is divided into a straight down type LED backlight optical system and a side entry LED backlight optical system.Due to the side entry type LED backlight optical system utilization is low and does not apply to local dynamic adjustment.Therefore,this design uses a direct backlight structure for local dynamic dimming of the LED backlight optical system..Straight down type LED backlight optical system under the light from the light source in the direct effect on the optical film,it has a simple structure,the advantages of saving energy consumption,the application of local dynamic dimming has many advantages,such as long time can reduce the full display of the lighting model bring burden to our eyes,and can also let the highlight of the entire screen.In this paper,we study the four different modes of illumination,such as full-screen illumination,central lighting,edge illumination and random illumination.The illumination uniformity and center point brightness of four different lighting modes in the traditional straight LED backlight system are emphatically studied.Application of synchronous multi-surface 3D technology,the optimal optimization method of free curved lens with square spot is analyzed,The generatrix is obtained by iterative method of function relation and fitted to form a free surface lens.The improved free surface lens has different light Angle and spot shape.Using the nine-point method to analyze the illumination uniformity of the light spot,the free surface lens is applied to the straight LED backlight optical system.Application of different mode of light cloth,the performance difference of the traditional LED backlight optical system and the improved LED backlight optical system in the light distribution mode,the light angle,the illuminance uniformity and the center brightness are compared.